The present invention relates to a refrigerant control of a refrigerator, and more particularly to a driving device for a motor-driven refrigerant three-way valve.
A conventional motor driven refrigerant three-way valve is categorized into a first type of the motor driven refrigerant three-way valve in which a valve is opened/closed by turning a resin disc valve, and a second type of the motor driven refrigerant three-way valve in which a valve is opened/closed by moving a steel ball, and operable in any of four modes; a) opening-closing mode, b) closing-closing mode, c) closing-opening mode, and d) opening-opening mode.
In the resin valve of the first type, the resin disc valve is turned while being in close contact with the valve port. Accordingly, a design of the 4-mode construction is easy. In the resin valve, the rotating face of the resin disc valve is slid in a state that it is strongly pressed for the purpose of leak prevention. Torque loss of the sliding friction is large, and the friction of the rotating face adversely affects the life of the valve. If the interval of the valve ports arranged and the diameter of the valve port are set to be large, a large operating torque is needed. Therefore, limitation is imparted also to the design of the interval of the valve ports and the diameter of the valve port.
In the ball valve of the second type, the valve ports may be arranged in a line. The opening and closing operations of the valve are performed through the rolling of the ball. Accordingly, the torque loss is small, and a high freedom is secured in arranging the valve ports and selecting the hole diameter. Even if the rotor accuracy is lowered, a pressing force may be concentrated onto the ball valve. As a result, the leak is small and the product quality is easily stabilized. To achieve the opening-opening mode in item xe2x80x9cdxe2x80x9d above of the four modes for the valve ports, which are arranged on both sides of the rotary shaft of the valve operation cam and on a diameter line while being equidistantly spaced from each other, the valve operating cam must cope with both the completely reverse operations, i.e., opening and closing operations, at the same position: both the valves are simultaneously closed at 0xc2x0 of the rotational angle of the valve operation cam, and simultaneously opened also at 180xc2x0. This makes it difficult to construct such a mechanism.
To cope with this, a conventional technique employs an xe2x80x9copening-opening modexe2x80x9d such that a guide for this mode is additionally provided, and rotor contact, which comes into contact with the rotor for controlling the ball valve, is provided on the end face of a guide bent part. It is placed on the guide, and the whole rotor is lifted along the edge of the guide to thereby release the ball valves. To the xe2x80x9copening-opening modexe2x80x9d construction, two ball valves must simultaneously be moved from their positions aligned with the valve ports. Accordingly, two rotor projections acting on the ball valves must be provided.
In the three modes; a) opening-closing mode, b) closing-closing mode, c) closing-opening mode, one of the rotor projections must be located outside the functional range. Accordingly, the mode selection must be performed within an extremely narrow range. In this respect, high precision is required for the shape and dimensions of the rotor. When the requirements for the mechanical position and precision are strict, high precision is required for the stopping position of the corresponding motor. To prevent a shift of the rotational position, in the case of the DC motor, a position sensor is needed since variations of an inertia movement amount, a movement amount at the time of non-constant torque, and the like are present. In the case of the stepping motor drive, a measure must be taken for an operation failure since a recognition difference by the circuit at the mechanical original point, a shift between the magnetizing position and the cam position, and the like are present. When the sliding part formed by the motor and the guide is an additionally part, it receives a crimping force corresponding to an acting pressure. Accordingly, the valve life is adversely affected.
Accordingly, an object of the present invention is to provide a ball-valve type motor-driven refrigerant three-way valve which is reliably operable, with a simple construction, in any of the four modes, xe2x80x9copening-closingxe2x80x9d, xe2x80x9cclosing-closingxe2x80x9d, xe2x80x9cclosing-openingxe2x80x9d,and xe2x80x9copening-openingxe2x80x9d modes, and is reliable and durable.
In order to achieve the above object, according to the present invention, there is provided a valve driving apparatus, comprising:
a first pipe, a second pipe and a third pipe, which are airtightly connected with each other;
a valve body;
a cam member, which rotates about a rotation axis for moving the valve body so as to open/close the first pipe and the second pipe so that the third pipe is selectively communicated with the first pipe and the second pipe, the cam member being movable in a direction parallel with the rotation axis; and
a cam actuator, which drives the cam member so as to move the cam member in the direction parallel with the rotation axis to open both of the first pipe and the second pipe, when the cam member is rotated at a predetermined angle.
According to the present invention, there is also provided a valve driving apparatus, comprising:
an inflow pipe;
an outflow pipe;
a casing body having an airtight chamber formed with openings respectively communicated with the inflow pipe and the outflow pipe;
a valve body;
a cam member, which provides an urging force on the valve body in such a direction that the valve body closes at least one of the openings;
a cam driver, which provides a driving force for rotating the cam member; and
a cam actuator, which moves the cam member against the urging force such that the openings are simultaneously opened.
The cam actuator includes: a seesaw portion, which performs a seesaw action in which the urging force moves the cam actuator and the seesaw portion moves the cam member against the urging force as a reaction; and an actuating portion, which moves the valve body to simultaneously open the openings when the seesaw action is performed.
For the simplicity, the cam member provides the urging force by utilizing the driving force of the cam driver, and a direction in which the cam member is moved as the reaction of the seesaw action is a direction parallel with a direction in which the urging force acts.
The seesaw portion extends in a direction perpendicular to a rotation axis of the cam member. A first position at which the urging force is applied is situated in a first end portion of the seesaw portion. The first position serves as a fulcrum of the seesaw action. A second position at which be actuating portion is provided is situated in a second end portion of the see saw portion. A slider which moves the cam member is situated at a third position closer to the second position.
The valve driving apparatus further comprises a guide member which restricts a direction in which the seesaw action is performed. The valve body is spherical body which is urged by an urging member so as to close the openings. The guide member restricts a position of the valve body.
The valve driving apparatus further comprises: a rotor, integrated with the cam member, and a stator, provided an outer periphery of the casing body. A motor formed by the rotor and the stator constitutes the cam driver.
Thus, a large mode selection angle is secured by merely adding one member, that is, the cam actuator. Accordingly, the requirements for the part precision and the assembling precision are lessened, in the cam actuator, the second position side of the seesaw portion is made heavy, so that the weight balance by the own weight is usually kept.
Accordingly, the invention succeeds in providing a valve driving apparatus capable of reliably controlling the four modes, xe2x80x9copening-closingxe2x80x9d, xe2x80x9cclosing-closingxe2x80x9d, xe2x80x9cclosing-openingxe2x80x9d, and xe2x80x9copening-openingxe2x80x9d modes, and is reliable and durable.